Pion Elastic and Charge-Exchange Scattering on p-Shell Nuclei by Isobar-Doorway State Model

The purpose of the present paper is to extend the isobar-hole model (i.e., the conventional isobar-doorway state model for the pion-nucleus reaction, to open-shell nuclei) by reformulating the model, and also to study the elastic scattering of pions from p-shell nuclei, the analyzing power and the charge-exchange reaction. For this purpose, we use the projection operator formalism, and take into account the correct center-of-mass transformation and the off-shell behavior of the pion-nucleon scattering amplitude. We assume a realistic nuclear model, i.e. the p-shell nuclear model of Cohen and Kurath. By studying elastic scattering from C and N, and the analyzing power and the charge-exchange reaction with C and N, we confirm the existence of the Lane term in the spreading potential implied by Hirata et al.